Design an experiment to determine the optimal temperature for enzyme function, complete with controls.
Lab 4: Enzymes
ANSWER KEY
Pre-Lab Questions
1. How could you test to see if an enzyme was completely saturated during an experiment? (2 pts)
To test this, you’d simply see if the reaction was still taking place. If the enzyme was completely depleted, the reaction could no longer occur.
2. List three conditions that would alter the activity of an enzyme. Be specific with your explanation. (2 pts)
Temperature, salinity, and acidity are three conditions that affect enzyme activity. Specific examples include:
Adding a salt packet to an enzyme would alter its activity–salt ions are often necessary for optimal enzyme activity, so too much or too little salt will slow down the rate.
Enzyme activity increases with increasing temperature, until it becomes hot enough to denature the protein (enzymes are proteins), then the activity would cease.
Enzymes have an optimum pH where they function the best. Higher or lower pH than the optimum slows the rate of activity.
3. Take a look around your house and identify household products that work by means of an enzyme. Name the products, and indicate how you know they work with an enzyme. (2 pts)
Some examples include: contact lens cleaner (protease), dish soap (amylase), cheese
(rennin), meat (papain), and starch products (amylase).
The rest of the questions that are answered:
Experiment 1: Enzymes In Food
Data Tables and Post-Lab Assessment
Table 1: Substance vs. Starch Presence
| Substance | Resulting Color | Presence of Starch? |
| Positive Control: Starch | ||
| Negative Control: Student Must Select | ||
| Food Product: | ||
| Food Product: | ||
| Saliva: |
Post-Lab Questions
1. What were your controls for this experiment? What did they demonstrate? Why was saliva included in this experiment?
2. What is the function of amylase? What does amylase do to starch?
3. Which of the foods that you tested contained amylase? Which did not? What experimental evidence supports your claim?
4. Saliva does not contain amylase until babies are two months old. How could this affect an infant’s digestive requirements?
5. There is another digestive enzyme (other than salivary amylase) that is secreted by the salivary glands. Research to determine what this enzyme is called. What substrate does it act on? Where in the body does it become activated, and why?
6. Digestive enzymes in the gut include proteases, which digest proteins. Why don’t these enzymes digest the stomach and small intestine, which are partially composed of protein?
Experiment 2: Effect of Temperature on Enzyme Activity
Data Tables and Post-Lab Assessment
Table 2: Balloon Circumference vs. Temperature
| Tube | Temperature (°C) | Balloon Circumference (Uninflated; cm) | Balloon Circumference (Inflated; cm) |
| 1 – (Cold) | |||
| 2 – (RT) | |||
| 3 – (Hot) |
Post-Lab Questions
1. What reaction is being catalyzed in this experiment?
2. What is the enzyme in this experiment? What is the substrate?
3. What is the independent variable in this experiment? What is the dependent variable?
4. How does the temperature affect enzyme function? Use evidence from your data to support your answer.
5. Draw a graph of balloon diameter vs. temperature. What is the correlation?
6. Is there a negative control in this experiment? If yes, identify the control. If no, suggest how you could revise the experiment to include a negative control.
7. In general, how would an increase in substrate alter enzyme activity? Draw a graph to illustrate this relationship.
8. Design an experiment to determine the optimal temperature for enzyme function, complete with controls. Where would you find the enzymes for this experiment? What substrate would you use?